The invention relates to a batter mix comprising genetically modified potato starch (GMPS), a process for the production of said batter mix, the use of said batter mix for the production of food products, preferably batter coated food products, which may be pre-fried, frozen and then preferably cooked in a microwave oven, whereby the use of the genetically modified potato starch in the batter mix compositions results in unexpected superior organoleptic properties of the food product, especially crispness.
Batter coated fried foods are broadly used. Among the most popular batter coated foods are fried chicken, fish and other meat products. EP-B1-0157800 relates to batters containing high amylose flour extracted from corn and wheat suitable for microwaveable pre-fried foodstuffs. Batter formulations for coating of foodstuff are described, consisting of starch containing products, egg solids, baking powder, cream, preservatives, seasonings, coloring and milk solids. The starch ingredient consists of a high amylose flour containing at least 50% amylose (on total starch) and other starches.
U.S. Pat. No. 5,104,669 relates to microwaveable flour-starch based food product and describes a mixture for a flour-starch-based food product, that heats evenly from a frozen condition, when exposed to microwave energy. The dough formula described herein includes 15-60% high amylose starch extracted from corn besides the flour and water.
WO 93/03634 A1 teaches a microwaveable coating based on starch and cellulose. or the purpose of obtaining crispy food following to heating after previous cooling, a predust formula consisting of high amylopectin starch and methyl cellulose is described, together with a batter formulation consisting of high amylose starch (40-50%), flour (25-40%) and cellulose gum (1-5%).
Many food products cooked by means of microwaving or baking do not show great qualitative differences. Frozen pre-fried foodstuffs however, exhibit great disadvantages when cooked final products are compared, which have been fried, baked or microwaved. In particular, microwaved products show great tendency to be undesirably soggy. There are at least two reasons known for that effect. Firstly, during microwaving, the moisture in the food piece is driven outwards towards the surface, which can cause the food piece to become soggy. During frying or baking, the outer coating receives the most exposure to high temperatures, thus providing a crispy outer coating. Secondly, microwave ovens are limited to a cooking temperature that does not exceed the boiling point of the water and thus, oil retained on or in a food piece after pre-frying will not continue to cook the food piece resulting in a different temperature gradient within the food piece. For example, crispness is an important criterion of pre-fried batter-coated food products which are cooked in a microwave oven.
Beside the fact that a batter mix which provides a crispy pre-fried batter-coated food piece after microwaving is highly desired, the mix must additionally provide other properties in order to obtain an acceptable food product. For example, the interface between the batter coating and food piece after microwaving should preferably be undistinguishable. The crispness of a batter-coated food piece becomes overshadowed as the interface worsens by going from thin and dry to floury, bready and finally to pasty. Avoidance of oil-weepage is also an important factor. Fluid migration during freezing or microwaving due to gravity may result in the pooling or fluids on the underface of the product resulting in a food product which is soggy beneath crispy coating. The batter should also provide good adhesion and cohesion in order to sustain the pressure of moisture. Some batters produce a lacy uneven coating on food pieces. Such a trait is also undesirable because it leads to crumbly coatings. Additionally, the batter should provide a food product with an acceptable and appealing final color.
Based on the great popularity of batter coated and optionally pre-fried food products, there are a number of various batter formulations and coating procedures known but the use of a genetically modified potato starch for the preparation of batter mixes has not been reported up to now.
Therefore, there is a strong need for the availability of batter mixes resulting in food products, in particular, batter-coated food products having improved features like superior crispness, improved taste and mouth-feeling.
It is well known that starch is composed of two fractions, the molecular arrangement of one being linear and the other being branched. The linear fraction of starch is known as amylose and the branched fraction as amylopectin. Methods for separating starch into these two components are known. Starches from different sources, e.g. potato, corn, tapioca, and wheat etc. are characterized by different relative proportions of the amylose and amylopectin components. Some plant species have been genetically developed by classical breeding which are characterized by a large preponderance of the one fraction over the other. For instance, certain varieties of corn which normally contain 22-28% amylose have been developed which yield starch composed of over 50% amylose. These hybrid varieties have been referred to as high amylose corn or amylomaize.
WO 97/11188 A1 teaches genetically modified potato plants producing a high amylose starch of up to about 70% and a decreased phosphate content of about only 10%. WO 97/11188 A1 relates to nucleic acid molecules which code for a starch-granule-bound protein, and a process and recombinant DNA molecules for the production of transgenic plants which synthesize a modified starch with altered viscosity properties and an altered (i.e. decreased) phosphate content compared to starch obtainable from non-transgenic potato plants. The introduction of the coding sequences of plasmids p35S-anti-RL and p35SH-anti-BE into the genome of potato plants is described. The plasmids had been introduced into the genome of the potato plant by using Agrobacterium tumefaciens mediated plant transformation. Plants had been regenerated and selected for the level of reduction of the expression of branching enzyme and RL-enzyme (R1 protein).
Surprisingly, it has now been found that the application of a certain genetically modified potato starch in batter mix compositions results in the improvement of food products exhibiting superior features, like improved organoleptic properties, in particular increased crispness, especially of microwaved pre-frozen food products prepared by use of said batter mix, in particular being coated with a batter mix according to the invention. Furthermore, the use of genetically modified starch in comparison to chemically modified starches is highly advantageous as complex and energy-consuming modification of the starch is avoided. It was additionally surprising, that especially pre-fried or fried comestibles exhibit a superior crispness after cooking in a microwave oven when prepared with the batter mix of the invention. The crispness maintains, even when the comestible is warmed up.
Therefore, the present invention relates to a batter mix, wherein a genetically modified potato starch (GMPS, GMP starch) having a phosphate content less than 85%, preferably less than 50%, more preferably less than 30% and most preferably less than 15% of the corresponding potato starch obtainable from a naturally occurring (i.e., a genetically not modified potato plant) plant is mixed with suitable batter mix ingredients. In this context, the total amount of phosphate in the starch is generally less than 11 nmol glucose-6-phosphate (G6P) per mg starch, preferably less than 7 nmol G6P/mg, more preferably less than 3,5 nmol G6P/mg, and most preferably less than 2 nmol G6P/mg starch. The phosphate content of the starch is to be identified according to the method described in example 8 b of WO 97/11188 A1 via determination of the glucose-6-phosphate amount per mg starch by an enzymatic assay using G6P-dehydrogenase. In another embodiment of instant invention the GMPS exhibits additionally an increased amylose content of at least 25%, preferably about 25-45% and in particular about 30-40% by weight of the total amount of starch. Usually, the amylose content of starch obtained from non genetically modified potato plants is about 20% by weight. The amylose content is determined according to the method of Hovenkamp-Hermelink et al. (Hovenkamp-Hermelink et al., 1988, Potato Research 31: 241-246). In still another preferred embodiment of instant invention the GMPS exhibits in addition a gel strength of about 90-160 g, preferably of about 100-160 g determined by a Texture Analyzer TA-XT2 (Stable Micro Systems, UK) as described below.
In the context of the present invention the term xe2x80x9cbatter mixxe2x80x9d means a mix of GMPS and other ingredients which are suitable in food industry for the preparation of batter mix compositions. The term xe2x80x9cbatter mixxe2x80x9d comprises, if not otherwise stated, dry and/or wet (i.e., aqueous) batter compositions, e.g., batters, dusted coatings, double coatings, films, film-coatings, glazes and the like. Usually, wet batter mixes comprise a dry matter or a GMPS of about 5 to 60%, preferably about 10 to 50% and most preferably about 15 to 40% by weight, depending on the viscosity and the use of the wet batter composition. Accordingly, the batter mix of the invention can be used for all coating applications of comestibles, for example the said films, glazes, dusted coatings, and double coatings.
The term xe2x80x9cgenetically modified potato starchxe2x80x9d (GMPS, GMP-starch) as used herein means a starch extracted from a potato plant that had been modified by use of genetic engineering with respect to its phosphate content and/or side chain distribution, preferably exhibiting an decreased phosphate content and/or increased amylose/amylopectin ratio compared to a naturally occurring potato starch. It is well known in the art how to obtain such GMPS by a large number of references regarding the production of transgenic potatoes by use of suitable genetic elements. GMPS are known, for example, from WO 90/12876 A1, WO 91119806 A1, WO 92/11375 A1, WO 92/11376 A1, WO 92/11382 A1, WO 92/14827 A1, WO 94/09144 A1, WO 94128149 A1, WO 95/04826 A1, WO 95/07355 A1, WO 95/26407 A1, WO 95/34660 A1, WO 95/03513 A1, WO 96/15248 A1, WO 96/19581 A1, WO 96/27674 A1, WO 96/34968 A1, WO 97/04112 A1, WO 97/04113 A1, WO 97/11188 A1, WO 97/20040 A1, WO 97/42328 A1, WO 98/11181 A1, WO 98/11228 A1, WO 98/37213 A1, WO 98/37214 A1, CA 2,061,443, DE 19836098.3, EP 0 455 316, EP 0 703 314, EP 0 737 777, EP 0 779 363, and U.S. Pat. No. 5,300,145. WO 97/11188 A1 extensively describes the preparation of the GMPS used in the examples hereinafter. Therefore, the contents of WO 97/11188 A1 are hereby explicitely incorporated by reference.
Furthermore, the invention relates to a process for the production of a batter mix according to the invention, wherein said genetically modified potato starch is mixed with suitable batter mix ingredients in order to obtain a dry or wet batter mix composition, and also the use of genetically modified potato starch (GMPS) for the production of batter mix compositions suitable for the preparation of food products or batter coated food products.
xe2x80x9cSuitable batter mix ingredientsxe2x80x9d are well known in the art and encompass natural occurring starches and/or flours mainly from corn, wheat, potato, tapioca, rice, genetically modified starches and/or flours from said crops other than potato, chemical and/or physical treated or modified starches and/or flours from said crops, cellulose gums or derivatives (ethers etc.), dextranes, in food industry suitable oligo-,di- and monosaccharides, inorganic and/or organic salt, flavors, stabilizers, egg solids, baking powder, cream of tartar, seasonings, coloring matter, milk solids, emulsifiers, spices, and additives.
The dry batter mixes are either directly used for predust or dust application of the comestible or are suspended in water so as to obtain the desired viscosity of a wet batter mix whereupon the batter mix is applied to the food pieces by means of a dip, spray or cascade technique and the like.
Another embodiment of the invention relates to the use of the batter mix according to the invention for the preparation of food products, preferably a batter coated food product. In particular, the food product is selected from the group consisting of red-meat, poultry, fish, vegetables, fruits, mushrooms, and cheese. Preferably, the batter coated food product will be exposed to microwave radiation before final food consumption which can be done for example in a microwave oven.
A further embodiment of the invention is the use of the batter mix of the invention for the improvement of crispness of a frozen comestible, in particular a batter-coated comestible, after microwave-heating or the improvement of crispness of a batter-coated comestible after oven treatment.
Still another embodiment of the invention is the food product comprising a batter mix according to the invention, or a food product which can be produced by use of the batter mix according to the invention, preferably a food product coated by a batter mix of the invention, and more preferred a food product selected from the group consisting of meat, poultry, fish, vegetables, fruits, mushroom, or cheese, and the process for the preparation of the said food products by use of the batter mix of the invention.
Before coating and/or frying, the batter coated food products may be also coated with a breading such as cereals, corn meal, corn flakes, cracker crumbs, bread crumbs, biscuit crumbs or the like, preferably having an average particle size of about 0.05 to 3.0 mm.
Finally, the invention relates to a process for the production of a food product according to the invention, wherein a batter mix according to the invention is used for the preparation of said food product, which is preferably selected from the group consisting of red-meat, fish, vegetables, fruits, mushrooms, and cheese and more preferred a batter coated food product.
To determine gel strength using a Texture Analyzer, 2 g of starch is gelatinized in 25 ml of water (cf. measurement using RVA) and then kept sealed air-tight for 24 h at 25xc2x0 C. The samples were fixed under the probe (round piston) of a Texture Analyzer TA-XT2 (Stable Micro Systems) and the gel strength was determined using the following parameter settings:
Test speed 0.5 mm/s
Depth of penetration: 7 mm
Contact surface (of the piston) 113 mm2 
Pressure/contact surface 2 g